Topological cascade laser for frequency comb generation in $\mathcal{PT}$-symmetric structures

TL;DR

This paper demonstrates a topological cascade laser in $\ ext{PT}$-symmetric structures that emits a stable frequency comb, leveraging topological edge modes in Aubry-Andr\'e-Harper lattices for potential applications in spectroscopy and quantum information.

Contribution

It introduces a novel topological cascade laser design utilizing $\ ext{PT}$-symmetry breaking to generate frequency combs with robust spectral features.

Findings

Laser emission with a frequency comb spectrum is achieved.

Topological protection ensures robustness of the spectral features.

Design flexibility allows for application-specific spectral engineering.

Abstract

The cascade of resonant topological structures with $\mathcal{PT}$-symmetry breaking is shown to emit laser light with a frequency-comb spectrum. We consider optically active topological Aubry-Andr\'e-Harper lattices supporting edge-modes at regularly spaced frequencies. When the amplified resonances in the $\mathcal{PT}$-broken regime match the edge modes of the topological gratings, we predict the emission of discrete laser lines. A proper design enables to engineer the spectral features for specific applications. The robustness of the topological protection makes the system very well suited for a novel generation of compact frequency comb emitters for spectroscopy, metrology, and quantum information.